A door was added, likely to make it harder for Tweek to reach his Flea level.

The scales were flipped and the switch was moved to the front, likely to make it easier to spot.

A whole new area was added in Viggo's Revenge, containing the exclusive Flamethrower weapon. Juliette cannot reach this place in other versions, and even if she could - There's nothing more than a wall there.

The Rumpus Room

Some stairs were removed. In Viggo's Revenge, you automatically return to the top upon completion of your task, and the area is sealed off.

A shelf was added with various equipment and some Viggo Industries paint cans.

An iron and ironing board were added. A Bungalow Telepoint has been added underneath the sink.